The S-400 batteries already have 96L6 radars on-site and deployed, so if these were intended for S-400s they'd likely represent new batteries that are forthcoming. That being said, deploying the 96L6 as an EW asset could make sense as well. There are a TON of older EW radars scattered about, and the 96L6 would make a useful replacement for the 36D6 series.

-Provides monitor of pulsed and continuous radar signals of air and naval source; IFF signals; determination of the signal parameters and radar type; trajectory tracking of aerial and naval targets using their emitted radio electric signals; passing on of collected information to PVO command posts.-Passive regime increases survivability of ECM and PVO units by 30-40%